On Mon, 24 Jun 2024, Jason Merrill wrote:
> On 6/24/24 21:00, Patrick Palka wrote:
> > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
> > for trunk/14?
> >
> > -- >8 --
> >
> > The capture proxy handling in finish_decltype_type added in r14-5330
> > was stripping the reference type of a capture proxy's captured variable,
> > which is desirable for a by-value capture, but not for a by-ref capture
> > (of a reference).
>
> I'm not sure why we would want it for by-value, either; regardless of the
> capture kind, decltype(x) is int&.
Ah, makes sense. But I guess that means
void f(int& x) {
[x]() {
decltype(auto) a = x;
}
}
is ill-formed since decltype(x) is int& but the corresponding closure
member is const? It works if we make the lambda mutable.
Like so? Bootstrapped and regtested on x86_64-pc-linux-gnu.
-- >8 --
Subject: [PATCH] c++: decltype of capture proxy of ref [PR115504]
The capture proxy handling in finish_decltype_type added in r14-5330
was stripping the reference type of a capture proxy's captured variable.
PR c++/115504
gcc/cp/ChangeLog:
* semantics.cc (finish_decltype_type): Don't strip the reference
type (if any) of a capture proxy's captured variable.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/decltype-auto8.C: New test.
---
gcc/cp/semantics.cc | 1 -
gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C | 18 ++++++++++++++++++
2 files changed, 18 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 6c1813d37c6..6a383c0f7f9 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12071,7 +12071,6 @@ finish_decltype_type (tree expr, bool
id_expression_or_member_access_p,
{
expr = DECL_CAPTURED_VARIABLE (expr);
type = TREE_TYPE (expr);
- type = non_reference (type);
}
else
{
diff --git a/gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
b/gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
new file mode 100644
index 00000000000..1100b94a5b7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
@@ -0,0 +1,18 @@
+// PR c++/115504
+// { dg-do compile { target c++14 } }
+
+void f(int& x) {
+ [&x]() {
+ decltype(auto) a = x;
+ using type = decltype(x);
+ using type = decltype(a);
+ using type = int&; // not 'int'
+ };
+
+ [x]() mutable {
+ decltype(auto) a = x;
+ using type = decltype(x);
+ using type = decltype(a);
+ using type = int&;
+ };
+}
--
2.45.2.648.g1e1586e4ed
>
> > PR c++/115504
> >
> > gcc/cp/ChangeLog:
> >
> > * semantics.cc (finish_decltype_type): For a by-reference
> > capture proxy, don't strip the reference type (if any) of
> > the captured variable.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * g++.dg/cpp1y/decltype-auto8.C: New test.
> > ---
> > gcc/cp/semantics.cc | 4 +++-
> > gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C | 11 +++++++++++
> > 2 files changed, 14 insertions(+), 1 deletion(-)
> > create mode 100644 gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
> >
> > diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> > index 08f5f245e7d..b4f626924af 100644
> > --- a/gcc/cp/semantics.cc
> > +++ b/gcc/cp/semantics.cc
> > @@ -12076,9 +12076,11 @@ finish_decltype_type (tree expr, bool
> > id_expression_or_member_access_p,
> > {
> > if (is_normal_capture_proxy (expr))
> > {
> > + bool by_ref = TYPE_REF_P (TREE_TYPE (expr));
> > expr = DECL_CAPTURED_VARIABLE (expr);
> > type = TREE_TYPE (expr);
> > - type = non_reference (type);
> > + if (!by_ref)
> > + type = non_reference (type);
> > }
> > else
> > {
> > diff --git a/gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
> > b/gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
> > new file mode 100644
> > index 00000000000..9a5e435f14f
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
> > @@ -0,0 +1,11 @@
> > +// PR c++/115504
> > +// { dg-do compile { target c++14 } }
> > +
> > +void f(int& x) {
> > + [&x]() {
> > + decltype(auto) a = x;
> > + using type = decltype(x);
> > + using type = decltype(a);
> > + using type = int&; // not 'int'
> > + };
> > +}
>
>
